Kate,
Like all of the side effects of radiation treatment, the answer is generally different for each of us. I'll relate my own experiences and hope it helps you.
I suffered from some pretty severe burns in relation to others going through the treament at the same time as I. Following the last rad treatment, it took about two weeks for the side effects to peak, and then the healing started. About two weeks after that, using Sulfadine cream and Vigilon pads, the sores and open wounds on my neck had healed. Another two weeks until the sores in my mouth and throat had healed, and I started weaning myself off of the pain patches. From there, for me, recovery went remarkably well. Much better than I had anticipated, and I was back to work full time 3 months after completion of treatment.
As I said though, recovery will be different for each of us. Hang in there though, the light at the end of the tunnel is NOT an oncoming train
Welcome to the site by the way. You will find many people here who have traveled the same path you are on, willing to help you in any way.
Take care of yourself, rest, eat, and heal.
Good Health,
Chuck